SALT LAKE CITY — Legal arguments before the U.S. Supreme Court about Utah's overturned same-sex marriage ban have focused heavily on whether gay and lesbians can be suitable parents, provoking a debate on family values in the Mormon state.

Lawyers for the state set the tone for the debate in a 100-page filing with the high court this week that made several references to their belief that children should be raised by straight couples. An attorney for same-sex couples says the state's argument has no scientific backing and that denying gays and lesbians the right to marry actually causes severe harm to their children.

More than 900 gay and lesbian couples have married since U.S. District Judge Robert Shelby ruled on Dec. 20 that the state's ban violates gay and lesbian couples' constitutional rights. The decision came as a shock to many in the state, where two-thirds of voters approved the ban on same-sex marriage in 2004.

This is the state's third attempt to have a court bring the gay marriages to a halt. Shelby and the 10th U.S. Circuit Court of Appeals have already refused to halt weddings while the state appeals what it calls a "rush to marry."

Sotomayor, who handles emergency requests from Utah and other Rocky Mountain states, can act by herself or get the rest of the court involved. It's unclear when she'll make a ruling.

In its filing Tuesday, Utah argued that children are best raised by a mother and father in a good relationship. Attorneys pointed to social science research that shows children do best when raised by a man and a woman. By upholding the ban, the state can ensure more children are raised in the optimal environment, attorneys argued.

"On average, children navigate developmental stages more easily, perform better academically, have fewer emotional disorders and become better functioning adults when reared in that environment," it says.

Peggy Tomsic, an attorney representing three gay and lesbian couples in Utah, fired back at the state's premise. She said the state's "hodgepodge of articles that purportedly show that same-sex parents are inferior to opposite-sex parents" is not only false, but fails to address the constitutional issues addressed in the ruling.

Same-sex couples agree that marriage provides enormous benefits to children, Tomsic argued, which is why gay marriages should be allowed to continue in Utah, where an estimated 3,000 children are being raised by same-sex couples.

"Excluding the children of same-sex couples from those benefits causes severe harm to those children, without providing any benefit to the children of opposite-sex parents," she wrote.

The heavily Mormon state wants the marriages to stop while until an appeals court reviews Shelby's decision. Tomsic said the state's request for an emergency stay on same-sex unions should be denied because Utah has not demonstrated how the weddings are harming anyone.

Page 2 of 2 - Nearly two-thirds of Utah's 2.8 million residents are members of The Church of Jesus Christ of Latter-day Saints, and Mormons dominate the state's legal and political circles. The Mormon church was one of the leading forces behind California's short-lived ban on same-sex marriage, Proposition 8.

Though the church has softened its stance toward gays and lesbians in recent years, the church still teaches that homosexual activity is a sin and stands by its support for "traditional marriage." Church officials say they hope a higher court validates its belief that marriage is between a man and woman.

In a hearing in early December, Tomsic contended that Utah's law is "based on prejudice and bias that is religiously grounded in this state."